Proteomics-based approach identifying autoantibody against peroxiredoxin VI as a novel serum marker in esophageal squamous cell carcinoma

Purpose: Detection of novel tumor-related antigens and autoantibodies will aid in diagnosis of early-stage cancer and in development of more effective immunotherapies. The purpose of this study was to identify novel tumor antigens in an esophageal squamous cell carcinoma (ESCC) cell line (TE-2) and related autoantibodies in sera from patients with ESCC using a proteomics-based approach. Experimental Design: TE-2 proteins were separated by two-dimensional PAGE, followed by Western blot analysis in which sera of patients with ESCC, healthy controls, and patients with other cancers were tested for primary antibodies. Positive spots were excised from silver-stained gels and analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/TOF MS). Results: Sera from patients with ESCC yielded multiple spots, one of which was identified as peroxiredoxin (Prx) VI by MALDI-TOF/TOF MS. Western blot analysis against recombinant Prx A showed reactivity in sera from 15 of 30 (50%) patients with ESCC and 2 of 30 (6.6%) healthy individuals. Autoantibody against PrxVI was found in sera from 1 of 30 (3.3%) patients with other types of cancer (colon cancer). Conclusion: We have identified for the first time an autoantibody against PrxVI in ESCC patients. The proteomic approach implemented here offers a powerful tool for identifying novel serum markers that may display clinical usefulness against cancer.